Physicochemical isotope anomalies
Abstract
Isotopic composition of refractory elements can be modified, by physical processes such as distillation and sputtering, in unexpected patterns. Distillation enriches the heavy isotopes in the residue and the light isotopes in the vapor. However, current models appear to be inadequate to describe the detailed mass dependence, in particular for large fractionations. Coarse- and fine-grained inclusions from the Allende meteorite exhibit correlated isotope effects in Mg both as mass-dependent fractionation and residual anomalies. This isotope pattern can be duplicated by high temperature distillation in the laboratory. A ubiquitous property of meteoritic inclusions for Mg as well as for most of the other elements, where measurements exist, is mass-dependent fractionation. In contrast, terrestrial materials such as microtektites, tektite buttons as well as lunar orange and green glass spheres have normal Mg isotopic composition. A subset of interplanetary dust particles labelled as chondritic aggregates exhibit excesses in {sup 26}Mg and deuterium anomalies. Sputtering is expected to be a dominant mechanism in the destruction of grains within interstellar dust clouds. An active proto-sun as well as the present solar-wind and solar-flare flux are of sufficient intensity to sputter significant amounts of material. Laboratory experiments in Mg show widespread isotope effects including residual {supmore »
- Authors:
-
- Australian National Univ., Canberra
- Publication Date:
- OSTI Identifier:
- 5557810
- Report Number(s):
- CONF-8703325-
Journal ID: ISSN 0016-7037; CODEN: GCACA
- Resource Type:
- Conference
- Journal Name:
- Geochimica et Cosmochimica Acta; (USA)
- Additional Journal Information:
- Journal Volume: 52:6; Conference: Isotope tracers in geochemistry and geophysics, Pasadena, CA (USA), 23-25 Mar 1987; Journal ID: ISSN 0016-7037
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 58 GEOSCIENCES; CHONDRITES; INCLUSIONS; CHEMICAL COMPOSITION; ISOTOPE RATIO; REFRACTORY METALS; DISTILLATION; GEOCHEMISTRY; GEOLOGIC HISTORY; GEOLOGIC MODELS; MAGNESIUM ISOTOPES; SOLAR FLARES; SOLAR WIND; TEKTITES; ALKALINE EARTH ISOTOPES; ALLOYS; CHEMISTRY; ELEMENTS; ISOTOPES; METALS; METEORITES; SEPARATION PROCESSES; SOLAR ACTIVITY; STONE METEORITES; 580400* - Geochemistry- (-1989)
Citation Formats
Esat, T M. Physicochemical isotope anomalies. United States: N. p., 1988.
Web.
Esat, T M. Physicochemical isotope anomalies. United States.
Esat, T M. 1988.
"Physicochemical isotope anomalies". United States.
@article{osti_5557810,
title = {Physicochemical isotope anomalies},
author = {Esat, T M},
abstractNote = {Isotopic composition of refractory elements can be modified, by physical processes such as distillation and sputtering, in unexpected patterns. Distillation enriches the heavy isotopes in the residue and the light isotopes in the vapor. However, current models appear to be inadequate to describe the detailed mass dependence, in particular for large fractionations. Coarse- and fine-grained inclusions from the Allende meteorite exhibit correlated isotope effects in Mg both as mass-dependent fractionation and residual anomalies. This isotope pattern can be duplicated by high temperature distillation in the laboratory. A ubiquitous property of meteoritic inclusions for Mg as well as for most of the other elements, where measurements exist, is mass-dependent fractionation. In contrast, terrestrial materials such as microtektites, tektite buttons as well as lunar orange and green glass spheres have normal Mg isotopic composition. A subset of interplanetary dust particles labelled as chondritic aggregates exhibit excesses in {sup 26}Mg and deuterium anomalies. Sputtering is expected to be a dominant mechanism in the destruction of grains within interstellar dust clouds. An active proto-sun as well as the present solar-wind and solar-flare flux are of sufficient intensity to sputter significant amounts of material. Laboratory experiments in Mg show widespread isotope effects including residual {sup 26}Mg excesses and mass dependent fractionation. It is possible that the {sup 26}Mg excesses in interplanetary dust is related to sputtering by energetic solar-wind particles. The implication if the laboratory distillation and sputtering effects are discussed and contrasted with the anomalies in meteoritic inclusions the other extraterrestrial materials the authors have access to.},
doi = {},
url = {https://www.osti.gov/biblio/5557810},
journal = {Geochimica et Cosmochimica Acta; (USA)},
issn = {0016-7037},
number = ,
volume = 52:6,
place = {United States},
year = {Wed Jun 01 00:00:00 EDT 1988},
month = {Wed Jun 01 00:00:00 EDT 1988}
}